The ecology of urban Vegetation: Trade-Offs, stressors, and adaptive strategies

Abstract

Urban vegetation has faced increasingly complex environmental stressors over the past 25 years. This review synthesizes peer-reviewed studies (2000–2025) using a PRISMA-based protocol to examine how key plant functional traits, such as leaf area index (LAI), air pollution tolerance index (APTI), and intrinsic water use efficiency (iWUE) respond to urban pressures including air pollution, heat islands, soil compaction, and fragmented green infrastructure. Our findings show trait effectiveness is context-dependent, varying by climate and urban form, with no universal indicator of resilience. We place particular emphasis on the role of climatic predictability and seasonal timing of stress exposure. Recent studies suggest that plant performance is shaped less by the absolute magnitude of drought or pollution and more by the recurrence and timing of these stressors, such as early-season droughts or late-summer ozone peaks. Physiological acclimation to dynamic environments thus becomes a critical criterion for species selection. Furthermore, city-type specificity emerged as a key factor: while compact Mediterranean cities face heat and water stress, tropical megacities are challenged by soil toxicity and spatial fragmentation. These findings reinforce the need to abandon generic planting lists and typological greening schemes in favor of differentiated, ecologically grounded strategies. Based on the reviewed literature and analytical framework, we propose measurable trait thresholds and adaptive design principles for urban vegetation planning. By integrating physiological resilience, spatial structure, and climatic background, urban planting strategies can be tailored to meet the demands of rapidly changing environmental conditions and ensure the long-term viability of vegetation.